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    Question

    ‘E’ takes 30 days to complete a job. If ‘F’ is

    50% more efficient than ‘E’, how many days will they take together to complete 75% of the work?
    A 4 days Correct Answer Incorrect Answer
    B 8 days Correct Answer Incorrect Answer
    C 6 days Correct Answer Incorrect Answer
    D 9 days Correct Answer Incorrect Answer

    Solution

    Let the work be 100x units.
    Efficiency of ‘E’ = 100x ÷ 30 = ‘10x/3’ units/day
    Efficiency of ‘F’ = (10x/3) × 1.5 = ‘5x’ units/day
    75% of the work = 100x × 0.75 = 75x units
    Required time = 75x ÷ ((10x/3) + 5x) = 75x ÷ ((10x + 15x)/3) = 75x ÷ (25x/3) = 9 days

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